Methods and systems for broad-band active noise reduction

Abstract

Described are methods and systems for broad-band active reduction of noise in target spaces, such as spaces around headrests in aircraft cabins. Systems describe herein are effective over wide frequency ranges without causing undesirable amplification at any subrange ranges. Specifically, a system comprises a speaker and a resonator, both coupled to an enclosure. The interior space of the resonator is in fluid communication with the enclosed space of the enclosure, allowing the resonator to reduce the amplitude of unwanted amplification by the audio reducing sound generated by the speaker. The amplitude is reduced in a selected frequency range, which may correspond to an expected amplification for this particular system. The resonator may partially extend into the enclosure or may be completely incorporated into the enclosure. Some examples of the resonator include a Helmholtz resonator, a passive radiator, a quarter wave resonator, a pipe resonator, and an acoustic metamaterial.

Description

BACKGROUND[0001]Various noise cancellation and reduction techniques, both active and passive, have been used to reduce unwanted ambient sounds. For example, an active system includes a speaker producing sound with the same amplitude but with the opposite polarity to the ambient sound. The system is designed such that the ambient and generated waves cancel each other thereby producing noise cancellation. However, active noise cancellation in free space has been challenging and generally limited to narrow frequency ranges. Furthermore, active noise reduction using conventional feedback methods tends to cause amplification of the noise at other frequencies. What is needed are methods and system for broad-band active noise cancellation.SUMMARY[0002]Described are methods and systems for broad-band active reduction of noise in target spaces, such as spaces around headrests in aircraft cabins. Systems describe herein are effective over wide frequency ranges without causing undesirable ampl...

AI Technical Summary

Benefits of technology

The patent describes methods and systems for reducing noise in target spaces, such as around headrests in aircraft cabins. The system includes a speaker and a resonator, which works by reducing the amplitude of the audio generated by the speaker. This resonator can work over wide frequency ranges without amplifying any specific subrange. The resonator can partially extend into the enclosure or be completely incorporated into it. The resonator can be designed using different methods like Helmholtz resonators, passive radiators, quarter wave resonators, pipe resonators, and acoustic metamaterials. Overall, this technology can help to reduce noise in target spaces and provide a more comfortable and relaxing environment for passengers.

Problems solved by technology

Expanding active noise control to free space applications has been limited because of less control, which may cause amplification rather than reduction of sound at certain frequencies and certain conditions as will now be described with reference to FIGS. 1A and 1B.

However, above 300 Hz, the noise has been amplified during this operation.

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